The invention relates to terminally functionalized liquid diene polymers and copolymers. More particularly, the invention relates to liquid diene polymers and copolymers containing terminals derived from fused-ring polynuclear aromatic compounds.
Diene polymers and copolymers containing certain terminal functional groups are known in the art. Such polymers depending on their particular terminal functional group exhibit reduced hysteresis properties in the carbon black reinforced and cured state and elastomeric compositions containing the polymers are often utilized to form tire treads having reduced rolling resistance and good traction properties. Diene polymers and copolymers of the aforementioned type are illustrated by the following patents:
U.S. Pat. No. 4,835,209 discloses the termination of living diene polymer or copolymer chains with carbodiimides. The patent discloses that rubber compositions containing such polymers have excellent performance characteristics with respect to tensile strength, impact resistance, low heat-generating properties and wear resistance without impairing wet skid properties.
U.S. Pat. No. 4,816,520 relates to terminally functionalized polymers, including diene polymers and copolymers and a process for their preparation. The reference discloses that the terminally functionalized polymers are prepared from living polymers obtained by anionic polymerization of olefinically unsaturated monomers by first reacting the living polymers with capping reagents comprising various nitrogen compounds including substituted imines (Schiff bases) and diaziridines and then reacting the capped polymer with a terminating agent which contains halogen or acid anhydride groups. Capping reagents which are disclosed include among others a compound of the formula ##STR1## wherein R.sub.1 is H, alkyl, cycloalkyl or aryl and R.sub.2 and R.sub.3 are each alkyl, cycloalkyl or aryl. Terminating agents which are disclosed include halogen compounds such as chloromethylstyrenes, acryloyl chloride, methacryloyl chloride, epichlorohydrin, etc.
U. S. Pat. No. 4,935,471 discloses the termination of living diene polymer or copolymer chains with a capping agent selected from the group consisting of (a) halogenated nitriles having the structural formula X--A--C.tbd.N wherein X is a halogen atom and A is an alkylene group of 1 to 20 carbon atoms, (b) heterocyclic aromatic nitrogen-containing compounds, and (c) alkyl benzoates. This patent discloses that compositions containing such polymers have reduced hysteresis and that tire treads made from such compositions have lower rolling resistance and better traction characteristics.